#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
#define ll long long
/*
hi, I'm rintaro.
AC is right
AC count is my life
But don't solve too many easy plobems!
*/
#define g(n,m) get<n>(m)
#define fof(i,o,n) for (ll i = o; i < (ll)n; i++)
#define fof_(dontuseit,a) for(auto &dontuseit : a)
#define vcin(a) fof_(i,a) cin>>i
#define all(o) o.begin(),o.end()
#define double long double
#define pii pair<ll,ll>
#define vec vector
#define vi vec<ll>
#define vs vec<string>
#define vc vec<char>
#define vvi vec<vi>
#define vpii vec<pii>
#define igpqueue priority_queue<ll,vi,greater<ll>>
#define re return
#define r0 re 0
#define ln(n) cout << n << endl
#define fix(n) << fixed << setprecision(n)
#define out_(n) << n << " "
#define Out cout
#define out(n) << n
#define End << endl
#define imap map<ll,ll>
#define smap map<string,ll>
#define gmap map<ll,vector<ll>>
#define m9 998244353
#define m7 1000000007
#define lny ln("Yes")
#define lnn ln("No")
int main() {
	string S, T;
	cin >> S >> T;
	if(S.size()>T.size()) {
		while(S.size()>T.size()) T='0'+T;
	}else {
		while(S.size()<T.size()) S='0'+S;
	}
	ll sum=0,mul=1;
	fof(i,0,S.size()) {
		if(S[S.size()-1-i]!=T[S.size()-1-i]) sum+=mul;
		mul*=2;
	}
	ln(sum);
}